Negative-polarity nanosecond-pulsed cryogenic plasma in liquid nitrogen

Abstract

Abstract In this work we report the results of imaging and spectroscopic measurements of the optical emission spectrum of a negative nanosecond-pulsed cryogenic discharge in liquid nitrogen. With the application of a lower electric field, the discharge first ignites as a ‘faint glow’ around the high-voltage needle electrode, but when the applied electric field reaches the transition value of around 5 MV cm−1 the discharge mode switches to a negative in-liquid streamer. The optical emission spectrum of the discharge is populated by the molecular nitrogen emission bands, and their analysis shows that the pressures and temperatures of the negative streamers in liquid nitrogen are at least of few tens of atmospheres and around 140–150 K. The results of this study demonstrate similarity of positive and neganive streamers in cryogenic in-liquid plasma conditions.